Gitwin - Enable your Windows system as a powerful and secure Git repository. Supports ssh, http(s) transports. Gitweb with highlighter and gravatar support available.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
LANState - LANState - Network Mapper and Device Monitor
NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.
Zenoss Core - Zenoss (Zenoss Core) is an open source application, server and network management platform based on...
Opsview Atom - Monitor everything. Integrate anything. Scale anywhere.